A typical spacecraft comprises a main body portion comprising a payload module and a bus module, a first solar wing, and a second solar wing. Each solar wing is selectively rotatably by a respective solar wing drive extending from diametrically opposite sides of the main body portion of the spacecraft. Each wing is connected to a boom which connects to a respective solar wing drive. The solar wings are typically planar and have solar cells on one side for converting sunlight into energy for powering the spacecraft.
Spacecrafts usually require four battery packs which supply energy for the spacecraft when the solar cells on the solar wings are not exposed to sunlight. These battery packs are typically secured at the four ends, or corners, of the bottom portion of the main body portion of the spacecraft to balance the weight of the battery packs. This particular placement of the battery packs, while adding stability to the spacecraft, also increases the height of the spacecraft. The height of the spacecraft is determinative of the size of the launch vehicle used for launching the spacecraft and/or the number of spacecrafts that can be launched per flight in a particular launch vehicle.
The main body portion of the spacecraft typically contains radiators for eliminating waste heat generated from the main body portion. The radiators are usually secured to the surfaces defining the main body portion, or can comprise the surfaces defining the main body portion, so that the radiators cover the main body portion. Radiators can also extend from the main body portion to maximize the elimination of spacecraft waste heat generated from the main body portion. Each battery pack has its own radiator which operates to eliminate waste heat generated from the battery pack. With the battery packs positioned on the bottom of the bus module, the height of the spacecraft is increased without increasing the available main body portion radiator space. It would be desirable to maximize the available area for main body portion radiators to maximize the spacecrafts ability to eliminate waste heat from the main body portion without increasing the size of the spacecraft.
Another problem with the positioning of the battery packs on the bottom side of the bus module, in addition to taking up space that could be used for main body portion radiators, is that the battery packs are susceptible to sunlight. Thermal loading from the sunlight operates to decrease the battery pack's operating life and efficiency.
Accordingly, it would be desirable to provide a spacecraft wherein the battery packs were positioned in such a manner as to increase available main body portion radiator area without increasing the size of the spacecraft. It would also be desirable to be able to decrease the height of a spacecraft without decreasing the available main body portion radiator area. It would also be further desirable to provide a spacecraft wherein the battery packs were positioned in such a manner as to reduce their exposure to sunlight thereby improving the battery pack's operating life and efficiency.